How to rotate a bone with time duration

mayank

Hi ,

I want to be able to rotate a bone with time duration. The one I am using is :

SkeletonData_findBone(mySkeleton->skeleton->data,"head")->rotation = 180;

But this simply repositions the bone "head" with a rotation of 180 degree.

What I want is that this rotation should be "visible" over a time duration. So for example it looks as if the bone is rotating from 0 to 180 degrees over a period of , lets say , 1 second.

How can I achieve this ?

thanks,
Best Regards,
Mayank

Søren

Basically you want to rotate by a small amount each frame in your render method. In Java you could do something like.

time += Gdx.graphics.getDeltaTime();
skeleton.findBone("head").setRotation(180*time);
skeleton.updateWorldTransform();

This will incrementally rotate the head by 180 degrees each second.

mayank

Thanks Shiu. I was aware of this ( in cocos2dx ), but I was wondering if Spine could handle it. Something like

// Instead of :: SkeletonData_findBone(mySkeleton->skeleton->data,"head")->rotation = 180; // rotate 180 degrees

SkeletonData_findBone(mySkeleton->skeleton->data,"head")->rotationtime(180,10); // rotate 180 degrees over 10 seconds

Doing it in "tick" or "render" method, will put a lot of load when there are many bones to rotate over a number of skeletons in one scene.

thanks,
Best Regards,
Mayank

Another way could be , I create an 'animation' in spine and name it , lets say "rotate". In this animation I always rotate by 30 degrees.

Now in code, if I can access this "animation" and change the value of rotation required, then it will be achieving the same thing. Then I can "tweak" the angle at run time.

Is that possible ? To change the values of an "animation" at runtime ?

Søren

My programming skills are sadly rather lacking. But are you asking if it's possible change the value of a specific key directly ?

Mitch

Doing it in "tick" or "render" method, will put a lot of load when there are many bones to rotate over a number of skeletons in one scene.

Sorry this is silly, having Spine handle it doesn't make it free, it just hides it. Just store a reference to the bone and rotate it somewhere so you don't have to use Find every cycle.

mayank

@Shiu ... yes that what I want ... I define an animation ( for rotation of a specific bone by 30 degrees )...now at runtime I will want to change the value to 60 degrees. Is that possible ? And how

@Mitch : You may be right. I have no idea how animation cycles are handled internally, but if your comment is based on the theory that "everything eventually gets scheduled in a time wheel", then you may be wrong. It depends on how the compiler handles or schedules the time wheel. I dont want to divulge this thread because what I am asking Shiu is different from what you and I are discussing. We can take it offline if you want, you can msg me 🙂 !

cheers !
Mayank

Søren

As far as I know you can't. Runtime manipulation is done to the setup pose and not the animated skeleton.

mayank

Oh. Too bad 🙁 . Hopefully it can be added in future